Hello.
I have just started to develope with QT. I understood a lot of things very fast, but I don't know one of the most important thing:

1. How can I change the active .ui file?
If I create a new GUI project, there is for example a MainWindow with his own .ui file.
I want to replace this .ui file with another .ui file, the .ui file from the class 'SecondWindow'. I don't know how to change the ui file which is shown in the window.

2. How can I show a second window?
I have a QMainWindow. If I press a QPushButton, I want to open a QWidget-window. How can I do this? How can I put this command into my slot?


Thanks.

[Sorry if you can't understand me. I'm German, but I tried to write as good as I can. ]